Integrated multi-color light emitting device made with hybrid crystal structure

ABSTRACT

An integrated hybrid crystal Light Emitting Diode (“LED”) display device that may emit red, green, and blue colors on a single wafer. The various embodiments may provide double-sided hetero crystal growth with hexagonal wurtzite III-Nitride compound semiconductor on one side of (0001) c-plane sapphire media and cubic zinc-blended III-V or II-VI compound semiconductor on the opposite side of c-plane sapphire media. The c-plane sapphire media may be a bulk single crystalline c-plane sapphire wafer, a thin free standing c-plane sapphire layer, or crack-and-bonded c-plane sapphire layer on any substrate. The bandgap energies and lattice constants of the compound semiconductor alloys may be changed by mixing different amounts of ingredients of the same group into the compound semiconductor. The bandgap energy and lattice constant may be engineered by changing the alloy composition within the cubic group IV, group III-V, and group II-VI semiconductors and within the hexagonal III-Nitrides.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalApplication No. 61/824,017 filed on May 16, 2013 entitled “INTEGRATEDMULTI-COLOR LIGHT EMITTING DEVICE MADE WITH HYBRID CRYSTAL STRUCTURE”,the entire contents of which are hereby incorporated by reference intheir entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The invention described herein was made in the performance of work undera NASA contract and by an employee of the United States Government andis subject to the provisions of Public Law 96-517 (35 U.S.C. §202) andmay be manufactured and used by or for the Government for governmentalpurposes without the payment of any royalties thereon or therefore. Inaccordance with 35 U.S.C. §202, the contractor elected not to retaintitle.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hybrid crystal light emitting diode(“LED”) display device and more particularly to a hybrid crystal LEDdisplay device that may emit red, green, and blue colors on a singlewafer.

2. Description of the Related Art

Today's Light Emitting Diodes (“LEDs”) are built with many compoundsemiconductors with type-I direct bandgap energies of two differentcrystal structures. While red, orange, yellow, yellowish green, andgreen LEDs are commonly made with III-V semiconductor alloys of aluminumgallium indium phosphide (AlGaInP) and aluminum gallium indium arsenide(AlGaInAs) with cubic zinc blende crystal structures, the higher energycolors such as green, blue, purple, and ultra-violet (“UV”) LEDs aremade with III-nitride compound semiconductors of AlGaInN alloys withhexagonal wurtzite crystal structures. Because the atomic crystalstructures are different for red LED and green/blue LEDs, theintegration and fabrication of these red and green/blue semiconductorLEDs as individual red (“R”), green (“G”), blue (“B”) pixels on onewafer has been extremely difficult.

BRIEF SUMMARY OF THE INVENTION

The various embodiments provide an integrated multi-color light emittingdevice (e.g., a light emitting diode (“LED”)) with a hybrid crystalstructure and methods for making the same. Various embodiments mayprovide an integrated hybrid crystal Light Emitting Diode (“LED”)display device that may emit red, green, and blue colors on a singlewafer. The various embodiments may provide double-sided hetero crystalgrowth with hexagonal wurtzite III-Nitride compound semiconductor on oneside of (0001) c-plane sapphire media and cubic zinc-blended III-V orII-VI compound semiconductor on the opposite side of c-plane sapphiremedia. In various embodiments the c-plane sapphire media may be a bulksingle crystalline c-plane sapphire wafer, a thin free standing c-planesapphire layer, or crack-and-bonded c-plane sapphire layer on anysubstrate. In various embodiments the bandgap energies and latticeconstants of the compound semiconductor alloys may be changed by mixingdifferent amounts of ingredients of the same group into the compoundsemiconductor. In various embodiments the bandgap energy and latticeconstant may be engineered by changing the alloy composition within thecubic group IV, group III-V, and group II-VI semiconductors and withinthe hexagonal III-Nitrides.

These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims, andappended drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate exemplary embodiments of theinvention, and together with the general description given above and thedetailed description given below, serve to explain the features of theinvention.

FIG. 1 illustrates a double sided hetero crystal structure with thehexagonal wurtzite AlGaInN structure on one side of the c-plane sapphireand the cubic zinc blende III-V or II-VI compound semiconductor, such asAlGaInP or AlGaInAs on the other side of the c-plane sapphire;

FIGS. 2A and 2B show the two distinct bandgap engineering diagrams inwhich the bandgap energies and the lattice constants of the compoundsemiconductor alloys may be changed by mixing different amounts ofingredients of the same group into the compound semiconductor;

FIG. 3 is a process flow diagram illustrating an embodiment method forfabricating a double sided hybrid crystal III-V/II-VI and III-Nitridecompound semiconductor wafer and integrated multi-color light emittingdevice;

FIG. 4 is multi-layer diagram of a double sided hybrid crystalIII-V/II-VI and III-Nitride compound semiconductor wafer according to anembodiment;

FIG. 5 is a fabricated device structure and circuit diagram formulti-color light emitting pixels according to an embodiment;

FIG. 6 is multi-layer diagram of a double sided hybrid crystalIII-V/II-VI and HE-Nitride compound semiconductor wafer according toanother embodiment; and

FIG. 7 is a fabricated device structure and circuit diagram formulti-color light emitting pixels according to another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of description herein, it is to be understood that thespecific devices and processes illustrated in the attached drawings, anddescribed in the following specification, are simply exemplaryembodiments of the inventive concepts defined in the appended claims.Hence, specific dimensions and other physical characteristics relatingto the embodiments disclosed herein are not to be considered aslimiting, unless the claims expressly state otherwise.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any implementation described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other implementations.

The various embodiments will be described in detail with reference tothe accompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.References made to particular examples and implementations are forillustrative purposes, and are not intended to limit the scope of theinvention or the claims.

Recently, a noble rhombohedral super hetero epitaxy technology has beendeveloped that can grow the (111) oriented single crystalline cubicsemiconductors, such as silicon germanium (SiGe), aluminum galliumindium phosphide (AlGaInP), and aluminum gallium indium arsenide(AlGaInAs), on a (0001) c-plane of trigonal substrate, such as asapphire (Al₂O₃) wafer. Examples of relevant epitaxial technologies aredescribed in U.S. Pat. No. 7,341,883 issued Mar. 11, 2008 entitled“SILICON GERMANIUM SEMICONDUCTIVE ALLOY AND METHOD OF FABRICATING SAME”,U.S. Pat. No. 7,514,726 issued Apr. 7, 2009 entitled “GRADED INDEXSILICON GERANIUM ON LATTICE MATCHED SILICON GERANIUM SEMICONDUCTORALLOY”, U.S. Pat. No. 7,558,371 issued Jul. 7, 2009 entitled “METHOD OFGENERATING X-RAY DIFFRACTION DATA FOR INTEGRAL DETECTION OF TWIN DEFECTSIN SUPER-HETERO-EPITAXIAL MATERIALS”, U.S. Pat. No. 7,769,135 issuedAug. 3, 2010 entitled “X-RAY DIFFRACTION WAFER MAPPING METHOD FORRHOMBOHEDRAL SUPER-HETERO-EPITAXY”, U.S. Pat. No. 8,226,767 issued Jul.24, 2012 entitled “HYBRID BANDGAP ENGINEERING FOR SUPER-HETERO-EPITAXIALSEMICONDUCTOR MATERIALS, AND PRODUCTS THEREOF”, and U.S. Pat. No.8,257,491 entitled “RHOMBOHEDRAL CUBIC SEMICONDUCTOR MATERIALS ONTRIGONAL SUBSTRATE WITH SINGLE CRYSTAL PROPERTIES AND DEVICES BASED ONSUCH MATERIALS”, the entire contents of all of which are herebyincorporated by reference in their entireties.

The various embodiments provide an integrated multi-color light emittingdevice (e.g., a light emitting diode (“LED”)) with a hybrid crystalstructure and methods for making the same. Various embodiments mayprovide an integrated hybrid crystal Light Emitting Diode (“LED”)display device that may emit red, green, and blue colors on a singlewafer. The various embodiments may provide double-sided hetero crystalgrowth with hexagonal wurtzite III-Nitride compound semiconductor on oneside of (0001) c-plane sapphire media and cubic zinc-blended III-V orII-VI compound semiconductor on the opposite side of c-plane sapphiremedia. In various embodiments the c-plane sapphire media may be a bulksingle crystalline c-plane sapphire wafer, a thin free standing c-planesapphire layer, or crack-and-bonded c-plane sapphire layer on anysubstrate. In various embodiments the bandgap energies and latticeconstants of the compound semiconductor alloys may be changed by mixingdifferent amounts of ingredients of the same group into the compoundsemiconductor. In various embodiments the bandgap energy and latticeconstant may be engineered by changing the alloy composition within thecubic group IV, group III-V, and group II-VI semiconductors and withinthe hexagonal III-Nitrides.

The various embodiments may be an extension of the double sided heterocrystal growth with the hexagonal wurtzite III-Nitride compoundsemiconductor on one side of (0001) c-plane sapphire media and cubiczinc-blende III-V or II-VI compound semiconductor on the opposite sideof c-plane sapphire media as shown in FIG. 1. FIG. 1 illustrates adouble sided hetero crystal structure with the hexagonal wurtzitestructure 102, such as a hexagonal wurtzite AlGaInN structure, on oneside of the c-plane sapphire 101 and the cubic zinc blende III-V orII-VI compound semiconductor 103, such as AlGaInP or AlGaInAs, on theother side of the c-plane sapphire 101. In various embodiments, thec-plane sapphire 101 media may be a bulk single crystalline c-planesapphire wafer, a thin free standing c-plane sapphire layer, orcrack-and-bonded c-plane sapphire layer on any substrate.

FIGS. 2A and 213 show the two distinct bandgap engineering diagrams inwhich the bandgap energies and the lattice constants of the compoundsemiconductor alloys may be changed by mixing different amounts ofingredients of the same group into the compound semiconductor. FIGS. 2Aand 2B show the change of the bandgap energy and lattice constants ofthe compound semiconductor alloy mixed from each pure compoundsemiconductor. Four classes of materials are shown; cubic crystalsinclude Group IV (Si, Ge, C), Group III-V (GaAs, AlAs, InAs, GaP, AlP,InP . . . ), and Group II-VI (ZnSe, CdS, HgTe . . . ). Hexagonalcrystals may include Group III-Nitride (GaN, AlN, InN). For example,GaAs and InAs may be mixed to form Ga_(1-x)In_(x)As alloy that may matchthe lattice constant of InP and the bandgap energy of 1.55 micrometerwavelength as marked as (i) in FIG. 2A. The bandgap energy and latticeconstant engineering by changing the alloy composition within the cubicgroup IV, group III-V, and group II-VI semiconductors and within thehexagonal III-Nitrides may be studied with a linear and quadraticapproximation (bowing parameter).

Although some of the cubic II-VI compound semiconductors could reachhigh energy near 3.8 eV with ZnS, the defect and auto-compensation ofp-type dopants in these materials may hinder the efficient blue lightemission from II-VI LED devices. Cubic III-V compound semiconductormaterials may have lower energy than 2.5 eV so that these materials mayonly emit IR, red, orange, yellow, and slightly yellowish green lights.III-V LEDs may not emit the blue, purple, and UV lights. On the otherhand, the hexagonal III-nitride compound semiconductor may emit highenergy lights such as green, blue, purple, and UV but may not emit thered and IR lights.

The various embodiments overcome the difficulties in the integration ofthese two different kinds of crystal structure materials through the useof rhombohedral hybrid epitaxy technology which may be guided by two newinnovative X-ray diffraction characterization methods. The variousembodiments may provide methods for integrating III-nitride layers onone side of the c-plane sapphire and [111] oriented rhombohedral III-Vor II-VI compound semiconductor layers on the other side of the samesapphire wafer.

FIG. 3 is a process flow diagram illustrating an embodiment method 300for fabricating a double sided hybrid crystal III-V/II-VI andIII-Nitride compound semiconductor wafer and integrated multi-colorlight emitting device. Example double sided hybrid crystal III-V/II-VIand III-Nitride compound semiconductor wafers that may be fabricated bythe operations of method 300 are illustrated in FIGS. 4 and 6 discussedfurther below, and example integrated multi-color light emitting devices(e.g., LEDs) that may be fabricated by the operations of method 300 areillustrated in FIGS. 5 and 7 discussed further below.

In block 302 a c-plane sapphire wafer may be provided and prepared forepitaxial growth. For example, the c-plane sapphire wafer may bedegreased and cleaned in preparation for epitaxial growth.

In an optional embodiment, in optional block 304 a heat absorbing layermay be deposited on the first side of the c-plane sapphire wafer. Asexamples, the heat absorbing layer may be carbon or titanium. The heatabsorbing layer may be optional if the sapphire wafer can be heated bydirect contact with a clean heater element or direct e-beam heating.Alternatively, the heat absorbing layer may be required for high vacuumprocesses.

In block 306 the substrate of the c-plane sapphire wafer may be heatedto a selected temperature and epitaxial layers of MN, GaN, InN, AlGaN,InGaN, and/or AlGaInN with proper dopants may be grown in selected layerstructures on the second side of the c-plane sapphire wafer. Theselected temperature may be a temperature and/or temperature range, suchas a temperature and/or temperature range from about 800° C. to about1200° C., a temperature and/or temperature range from about 700° C. toabout 1000° C., and/or a temperature and/or temperature range from about500° C. to about 900° C. The selected layer structures may be structuresdesigned to fabricate efficient LED structures, such as various p-typelayers, intrinsic layers, and n-type layers. As examples, one or morep-type layer may be grown comprised of AlGaN, InGaN, AlGaInN, MN, InN,or GaN doped with a p-type dopant, such as magnesium, one or more n-typelayer may be grown comprised of AlGaN, InGaN, AlGaInN, MN, InN, or GaNdoped with a n-type dopant, such as silicon, and one or more intrinsiclayer may be grown comprised of AlGaN, InGaN, AlGaInN, MN, InN, or GaN.Intrinsic layers may not need any dopants. The selected layer structuresmay be various combinations of various numbers of n-type layers, p-typelayers, and intrinsic layers extending from the second side of thec-plane sapphire wafer. As examples, extending from the second side ofthe c-plane sapphire wafer, the selected layer structures may be aseries of n-i-p-i-n layers, a series of p-i-n-i-p layers, a series ofn-i-p layers, a series of p-i-n layers, etc. In various embodiments,dopants for the various layers may be inserted during layer growth, ionimplantation, or through a dopant diffusion drive-in process. In someembodiments, in optional block 308 proper and/or additional dopants maybe provided to the layers.

Once all of the III-Nitride layers are fabricated, in block 310 aprotective layer, such as silicon oxide, silicon nitride, MN, or Al₂O₃,may be deposited over the III-Nitride layers. The protective layer mayseal and isolate the relatively delicate III-Nitride layers during thefollowing III-V or II-VI semiconductor fabrication processes.

In an optional embodiment in which an optional heat absorbing layer wasdeposited on the first side of the c-plane sapphire wafer, in optionalblock 312 the heat absorbing layer on the first side of the c-planesapphire wafer may be removed. For example, the heat absorbing layer maybe removed by etching, such as wet etching, plasma etching, reactive ionetching, etc., or by chemical mechanical polishing (“CMP”).

In block 314 the first side of the c-plane sapphire wafer may beprepared for rhombohedral III-V or II-VI epitaxy growth andrhombohedrally aligned III-V or II-VI compound semiconductor layers inselected layer structures may be gown on the first side of the c-planesapphire wafer. The selected layer structures may be structures designedto fabricate efficient LED structures, such as various p-type layers,intrinsic layers, and n-type layers, for low energy light emittingdevices, such as IR, red, orange, yellow, and green LEDs. As examples,one or more p-type layer(s) may be grown comprised of AlGaP, InGaP,InAlP, AlGaInP, AlP, InP, GaP, AlGaAs, InGaAs, InAlAs, AlGaInAs, AlAs,InAs, GaAs, AlGaPAs, InGaPAs, InAlPAs, AlGaIniPAs, AlPAs, InPAs, orGaPAs doped with a p-type dopant, such as magnesium, one or more n-typelayer(s) may be grown comprised of AlGaP, InGaP, InAlP, AlGaInP, AlP,InP, GaP, AlGaAs, InGaAs, InAlAs, AlGaInAs, AlAs, InAs, GaAs, AlGaPAs,InGaPAs, InAlPAs, AlGalInPAs, AlPAs, InPAs, or GaPAs doped with aii-type dopant, such as silicon, and one or more intrinsic layer(s) maybe grown comprised of AlGaP, InGaP, InAlP, AlGaInP, AlP, InP, GaP,AlGaAs, InGaAs, InAlAs, AlGaInAs, AlAs, InAs, GaAs, AlGaPAs, InGaPAs,InAlPAs, AlGaInPAs, AlPAs, InPAs, or GaPAs. Intrinsic layers may notneed any dopants. The selected layer structures may be variouscombinations of various numbers of n-type layers, p-type layers, and/orintrinsic layers extending from the first side of the c-plane sapphirewafer. As examples, extending from the first side of the c-planesapphire wafer, the selected layer structures may be a series of n-i-players, a series of p-i-n layers, a series of p-i-n-i-p layers, a seriesof n-i-p-i-n layers, a series of p-n layers, a series of n-p layers,etc. In various embodiments, dopants for the various layers may beinserted during layer growth, ion implantation, or through a dopantdiffusion drive-in process. In some embodiments, in optional block 316proper and/or additional dopants may be provided to the layers.

Once all the rhombohedral III-V or II-VI layers are fabricated, in block318 a protective layer, such as silicon oxide, silicon nitride, MN, orAl₂O₃, may be deposited over the rhombohedral III-V or II-VI layers. Theprotective layer may seal and isolate the relatively delicaterhombohedral III-V or II-VI layers from the environment and during anyfurther fabrication processes. The operations through block 318 mayproduce a double sided hybrid crystal III-V/II-VI and III-Nitridecompound semiconductor wafer.

In order to make a full multi-wavelength light emitting device, eachprotective layer may have to be removed by a masked etching process todefine one or more device areas on the wafer. In block 320 theprotective layer may be removed from the III-Nitride layers, deviceareas may be formed on the III-Nitride layers, and electrodes may beformed on the HI-Nitride layers to fabricate a III-Nitride LED devicestructure on the second side of the c-plane sapphire wafer. Theprotective layer may be removed and the device areas defined by maskedetching. Metal or transparent electrodes (e.g., Indium Tin Oxide (ITO)electrodes) may be formed to create a contact area to deliver positive(+) and negative (−) voltages and current. The protective layer over theIII-V or II-VI layers may remain in place while the III-Nitride LEDdevice structure is fabricated.

In block 322 a protective layer may be deposited over the III-NitrideLED device structure. In block 324 the protective layer may be removedfrom the rhombohedral III-V or II-VI layers, device areas may be formedon the rhombohedral III-V or II-VI layers, and electrodes may be formedon rhombohedral III-V or II-VI layers to fabricate a III-V or II-VI LEDdevice structure on the first side of the c-plane sapphire wafer. Theprotective layer may be removed and the device areas defined by maskedetching. Metal or transparent electrodes (e.g., ITO electrodes) may beformed to create a contact area to deliver positive (+) and negative (−)voltages and current.

By depositing, patterning, and removing materials through the standardlithography process, the integrated multi-wavelength light emittingdevices may be formed. One pixel may be made of red, green, and blueLEDs from the double sides of the sapphire wafer, such as IR, R, G, B,or Red, Yellow, Green, and Blue. Multiple arrays of these pixels may beused to make a flat panel display or a projector panel.

In an embodiment, the operations of blocks 302-324 may be performed in acontinuous process to produce an integrated multi-color light emittingdevice (e.g., an LED). In another embodiment, the operations of blocks302-318 may be wafer fabrication operations performed independent of theoperations of blocks 320-324 which may be device fabrication operations.For example, the wafer fabrication operations of blocks 302-318 may beperformed during a wafer manufacturing process to produce a double sidedhybrid crystal III-VIII-VI and III-Nitride compound semiconductor waferthat may be sold into the industrial commercial market. The double sidedhybrid crystal III-V/II-VI and III-Nitride compound semiconductor wafermay be purchased by a customer and the operations of blocks 320-324 maybe performed during a device manufacturing process to produce anintegrated multi-color light emitting device (e.g., an LED).

In an embodiment, the sequence of operations of method 300 may beexchanged, such that the operations for rhombohedral III-V or II-VIlayer formation may be performed first and the operations forIII-Nitride layer formation may be performed second. However, performingIII-Nitride layer formation first may be advantageous because thetypical growth temperature for III-V or II-VI semiconductors may belower than that of III-Nitride semiconductor growth.

FIG. 4 shows one type of an integrated multi wavelength light emittingdevice 400 made with a hybrid crystal according to an embodiment. Thedevice 400 may be a double sided hybrid crystal III-V/II-VI andIII-Nitride compound semiconductor wafer including a hexagonal structure102 on one side of a c-plane sapphire 101 and a III-V or II-VI compoundsemiconductor 103 on an opposite side as described above with referenceto FIG. 1. In this configuration, green and blue lights are generated inthe III-Nitride semiconductor layer (comprising layers 404, 406, 408,410, and 412), and the red light is generated in the rhombohedralIII-V/II-VI semiconductor layer (comprising layers 414, 416, and 418).An ii-type layer 404 or 412 (e.g., n-type layers comprised of AlGaN,InGaN, AlGaInN, MN, InN, or GaN) provides electrons into the intrinsicor low-doped layer 406 or 410 (e.g., intrinsic or low-doped layerscomprised of AlGaN, InGaN, AlGaInN, AlN, InN, or GaN) which has a lowerconduction band when a voltage is applied. A p-type layer 408 (e.g.,p-type layer comprised of AlGaN, InGaN, AlGaInN, AlN, InN, or GaN) inthe middle provides holes into the intrinsic or low-doped layer 406and/or 410 which has higher valence band when a voltage is applied. Thetwo intrinsic or low doped layers 406 and 410 may have optimizedcontents of indium, gallium, and aluminum, to change their bandgapenergies to that of blue and green photons, individually. For example,the alloy composition of the intrinsic or low doped layer 406 may beselected to bring the bandgap energy to that of the green photon (e.g.,wavelength of 500-590 nanometers (nm)) and the alloy composition of theintrinsic or low doped layer 410 may be selected to bring the bandgapenergy to that of the blue photon (e.g., wavelength of 400-500 nm). Theaccumulated electrons and holes in each intrinsic or low doped layer 406and 410 easily recombine and emit the blue and green lights. Aprotection layer or transparent electrode 420 may be present on theoutside surface of the III-Nitride semiconductor layer.

Although FIG. 4 shows a (Surface) n-i-p-i-n (Sapphire) structure ofdoping, other variation of layer structures can work. For example,(Surface) p-i-n-i-p (Sapphire) structure can work as well. Variations ofthese layers are also possible by inserting intrinsic or low doped AlNas a bather layer such as [1] (Surface) p-GaN i-GaInN n-GaN/AlN (as anelectric barrier)/p-GaN/i-InGaN n-GaN/c-plane Sapphire (Substrate) or[2] (Surface) p-GaN/i-GaInN/n-GaN/AlN (as an electricbarrier)/n-GaN/i-InGaN/p-GaN c-plane Sapphire (Substrate).

The rhombohedral III-V or II-VI LED structure (comprising layers 414,416, and 418) may be made on the opposite side of sapphire 402. From thesapphire side, n-type layer 414 (e.g., a n-type layer comprising AlGaP,InGaP, InAlP, AlGaInP, AlP, InP, GaP, AlGaAs, InGaAs, InAlAs, AlGaInAs,AlAs, InAs, GaAs, AlGaPAs, InGaPAs, InAlPAs, AlGaInPAs, AlPAs, InPAs, orGaPAs) provides electrons into the intrinsic or low-doped layer 416(e.g., an intrinsic or low-doped layer comprising AlGaP, InGaP, InAlP,AlGaInP, AlP, InP, GaP, AlGaAs, InGaAs, InAlAs, AlGaInAs, AlAs, InAs,GaAs, AlGaPAs, InGaPAs, InAlPAs, AlGaInPAs, AlPAs, InPAs, or GaPAs)while p-type layer 418 (e.g., a p-type layer comprising AlGaP, InGaP,InAlP, AlGaInP, AlP, InP, GaP, AlGaAs, InGaAs, InAlAs, AlGaInAs, AlAs,InAs, GaAs, AlGaPAs, InGaPAs, InAlPAs, AlGaInPAs, AlPAs, InPAs, orGaPAs) on the backside provides holes into the intrinsic, or low-dopedlayer 416. The accumulated electrons and holes recombine and emit thered lights. Similarly, variations of these structures also work such asn-i-p LED, p-i-n LED, or p-n LED, n-p LED structures. The intrinsic orlow doped layer 416 may have optimized contents of indium, gallium, andaluminum, to change the bandgap energy to that of red photons. Forexample, the alloy composition of the intrinsic or low doped layer 416may be selected to bring the bandgap energy to that of the red photon(e.g., wavelength of 590-700 nm). The thickness and alloy composition ofthe intrinsic or low-doped layers (e.g., intrinsic or low doped layers406, 410, and 416) may be selected such that the narrowest relativebandgap energy may be at the intrinsic or low-doped layer (e.g., 416)emitting red photons and the widest relative bandgap energy may be atthe intrinsic or low-doped layer (e.g., 410) emitting blue photons. Ifthe thickness and alloy composition of intrinsic or low-doped layers(e.g., layers 406, 410, and 416) are critically controlled, a quantumwell with discrete energy levels inside the layer may be formed. Thismay enhance the light emission efficiency. The variation of structurewith a quantum well LED, multiple quantum well, graded indexed channeledLED, and stepped LED structure may also be formed in this hybrid crystalLED.

FIG. 5 shows the fabricated multi-wavelength integrated hybrid lightemitting device 500 after all the post multilayer wafer processesincluding ITO deposit, lithography, etching, and metallization. Forexample, a Blue LED circuit and Green LED circuit may be formed byremoving a middle portion of layers 412, 410, 408, and 406 to create twoseparate columns extending from the layer 404. One column of layers 412,410, 408 a, and 406 a may be capped with a transparent electrode 420 ato form the Blue LED. The other column may have the layers 412 and 410removed leaving the layers 408 b and 406 b extending from the layer 404which may be capped with a separate transparent electrode 420 b to formthe Green LED. The rhombohedral III-V or II-VI LED structure may nothave material removed and may be capped with a metal electrode 422 toform the Red LED. Each circuit may drive the Red LED, Green LED, andBlue LED separately. The III-Nitride and sapphire may be transparent tothe red light so that the red light from the backside of the wafer maypropagate to the front surface of the wafer. Transparent electrodes suchas ITO or thin Graphene are used on the front side electrodes 420 a and420 b. Typical pixels 506, 504, and 502 may be made with the Red, Green,and Blue LEDs, respectively. More complex pixels may be formed with IR,R, G, and B. Different pixel color configurations may be made withselections from IR, Red, Orange, Yellow, Green, Blue, Purple, and UV.The array of the pixels may be used to build various devices, includinga flat panel display, outdoor display, a projector panel, a scannerlight source, or scientific optical instruments.

FIGS. 6 and 7 show another embodiment of an integrated multi-wavelengthlighting device in which the green and red lights may be generatedinside the rhombohedral III-V or II-VI layers. FIG. 6 shows anintegrated multi wavelength light emitting device 600 made with a hybridcrystal according to an embodiment. The device 600 may be a double sidedhybrid crystal III-V/II-VI and III-Nitride compound semiconductor waferincluding a hexagonal structure 102 on one side of a c-plane sapphire101 and a III-V or II-VI compound semiconductor 103 on an opposite sideas described above with reference to FIG. 1. AlGaP, InGaP, InAlP,AlGaInP, AlP, InP, GaP, AlGaAs, InGaAs, InAlAs, AlGaInAs, AlAs, InAs,GaAs, AlGaPAs, InGaPAs, InAlPAs, AlGaInPAs, AlPAs, InPAs, or GaPAs maybe used to make green, yellow, orange, and red colors. In theconfiguration illustrated in FIG. 6, only blue lights may be generatedin the III-Nitride semiconductor layer (comprising layers 604, 606, and608), and the green and red light may be generated in the rhombohedralIII-V/II-VI semiconductor layer (comprising layers 610, 612, 614, 616,and 618). A protection layer or transparent electrode 620 may be presenton the outside surface of the III-Nitride semiconductor layer and aprotection layer or metal electrode 622 may be present on the outsidesurface of the rhombohedral III-V/II-VI semiconductor layer.

An n-type layer 604 (e.g., n-type layers comprised of AlGaN, InGaN,AlGaInN, MN, InN, or GaN) may provide electrons into the intrinsic orlow-doped layer 606 (e.g., intrinsic or low-doped layers comprised ofAlGaN, InGaN, AlGaInN, AlN, InN, or GaN) which has a lower conductionband when a voltage is applied. A p-type layer 608 (e.g., p-type layerscomprised of AlGaN, InGaN, AlGaInN, AlN, InN, or GaN) in the middleprovides holes into the intrinsic or low-doped layer 606 which hashigher valence band when a voltage is applied. The accumulated electronsand holes in intrinsic or low-doped layer 606 easily recombine and emitthe blue light.

The rhombohedral III-V or II-VI LED structure (comprising layers 610,612, 614, 616, and 618) may be made on the opposite side of sapphire602. From the sapphire side, p-type layer 610 (e.g., a p-type layercomprising AlGaP, InGaP, MAW, AlGaInP, AlP, InP, GaP, AlGaAs, InGaAs,InAlAs, AlGaInAs, AlAs, InAs, GaAs, AlGaPAs, InGaPAs, InAlPAs,AlGaInPAs, AlPAs, InPAs, or GaPAs) provides holes into the intrinsic orlow-doped layer 612 (e.g., an intrinsic or low doped layer comprisingAlGaP, InGaP, InAlP, AlGaInP, AlP, InP, GaP, AlGaAs, InGaAs, InAlAs,AlGaInAs, AlAs, InAs, GaAs, AlGaPAs, InGaPAs, InAlPAs, AlGaInPAs, AlPAs,InPAs, or GaPAs) while from the lower surface side p-type layer 618(e.g., a p-type layer comprising AlGaP, InGaP, InAlP, AlGaInP, AlP, InP,GaP, AlGaAs, InGaAs, InAlAs, AlGaInAs, AlAs, InAs, GaAs, AlGaPAs,InGaPAs, InAlPAs, AlGaInPAs, AlPAs, InPAs, or GaPAs) provides holes intothe intrinsic or low-doped layer 616. The n-type layer 614 (e.g., an-type layer comprising AlGaP, InGaP, InAlP, AlGaInP, AlP, InP, GaP,AlGaAs, InGaAs, InAlAs, AlGaInAs, AlAs, InAs, GaAs, AlGaPAs, InGaPAs,InAlPAs, AlGaInPAs, AlPAs, InPAs, or GaPAs) on the backside provideselectrons into the intrinsic or low-doped layers 612 and 616. Theaccumulated electrons and holes recombine and emit the red and greenlights. In this manner, in device 600 illustrated in FIG. 6, green andred lights are made by two different rhombohedral intrinsic or low-dopedlayers and blue light is made by hexagonal intrinsic or low-doped layer.The intrinsic, or low doped layer 616 may have optimized contents ofindium, gallium, and aluminum, to change the bandgap energy to that ofred photons, the intrinsic or low doped layer 612 may have optimizedcontents of indium, gallium, and aluminum, to change the bandgap energyto that of green photons, and the intrinsic or low doped layer 606 mayhave optimized contents of indium, gallium, and aluminum, to change thebandgap energy to that of blue photons. For example, the alloycomposition of the intrinsic or low doped layer 616 may be selected tobring the bandgap energy to that of the red photon (e.g., wavelength of580-700 nm), the alloy composition of the intrinsic or low doped layer612 may be selected to bring the bandgap energy to that of the greenphoton (e.g., wavelength of 500-580 nm), and the alloy composition ofthe intrinsic or low doped layer 606 may be selected to bring thebandgap energy to that of the blue photon (e.g., wavelength of 400-500nm). The thickness and alloy composition of the intrinsic or low-dopedlayers (e.g., intrinsic or low doped layers 606, 612, and 616) may beselected such that the narrowest relative bandgap energy may be at theintrinsic or low-doped layer (e.g., 616) emitting red photons and thewidest relative bandgap energy may be at the intrinsic or low-dopedlayer (e.g., 606) emitting blue photons.

In device 700 of FIG. 7, while blue light is generated in the hexagonalintrinsic or low-doped layer (e.g., a i-AlGaInN layer), green and redlights are generated by two intrinsic or low-doped layers (e.g.,i-AlGaInP layers) with different alloy compositions and thicknesses.FIG. 7 shows the fabricated multi-wavelength integrated hybrid lightemitting device 700 after all the post multilayer wafer processesincluding ITO deposit, lithography, etching, and metallization. Forexample, a Blue LED circuit may be formed by capping the III-Nitridesemiconductor layer with a transparent electrode 620, the III-Nitridesemiconductor layer may not have material removed. The Red LED circuitand Green LED circuit may be formed by removing portions of layers 618and 616 to create a column extending from the layer 614. The column ofthe remaining portions of layers 618 and 616 may be capped with a metalelectrode 622 b to form the Red LED. A metal electrode 622 a separatefrom the column of layers 618 and 616 may be formed on the layer 614which may form the Green LED. Each circuit may drive the Red LED, GreenLED, and Blue LED separately. The III-Nitride and sapphire may betransparent to the red light and green light so that the red and greenlight from the backside of the wafer may propagate to the front surfaceof the wafer. Typical pixels 706, 704, and 702 may be made with the Red,Green, and Blue LEDs, respectively.

The working principles and device structure variations of devices 600and 700 may be similar to those described above with reference to FIGS.4 and 5.

In various embodiments, the wafer layer and device structures shown inthe FIGS. 4, 5, 6 and 7 may work as integrated photon detectors as well.The typical photon detector has p-i-n structures. The photon detectorsabsorb light and generate electric current and voltage that may be anopposite operation to the light emitting device operations describedabove.

The preceding description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the following claims and theprinciples and novel features disclosed herein.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety. However, if a termin the present application contradicts or conflicts with a term in theincorporated reference, the term from the present application takesprecedence over the conflicting term from the incorporated reference.

All ranges disclosed herein are inclusive of the endpoints, and theendpoints are independently combinable with each other. Each rangedisclosed herein constitutes a disclosure of any point or sub-rangelying within the disclosed range.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. “Or” means “and/or.” As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.As also used herein; the term “combinations thereof” includescombinations having at least one of the associated listed items, whereinthe combination can further include additional, like non-listed items.Further, the terms “first,” “second,” and the like herein do not denoteany order, quantity, or importance, but rather are used to distinguishone element from another. The modifier “about” used in connection with aquantity is inclusive of the stated value and has the meaning dictatedby the context (e.g., it includes the degree of error associated withmeasurement of the particular quantity).

Reference throughout the specification to “another embodiment”, “anembodiment”, “exemplary embodiments”, and so forth, means that aparticular element (e.g., feature, structure, and/or characteristic)described in connection with the embodiment is included in at least oneembodiment described herein, and can or cannot be present in otherembodiments. In addition, it is to be understood that the describedelements can be combined in any suitable manner in the variousembodiments and are not limited to the specific combination in whichthey are discussed.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope of the inventionis defined by the claims, and can include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral language of the claims.

What is claimed is:
 1. A double sided hybrid crystal and III-V/II-VI andIII Nitride compound semiconductor device comprising: a trigonalsapphire layer; a hexagonal III-Nitride structure grown from a firstside of the trigonal sapphire layer, wherein the hexagonal III-Nitridestructure has a bandgap energy equal to that of a blue photon having awavelength of 400-500 nm: and a rhombohedral III-V or II-VI structuregrown from a second side of the trigonal sapphire layer, wherein therhombohedral III-V or II-VI structure has a bandgap energy equal to thatof a red photon having a wavelength of 580-700 nm.
 2. The device ofclaim 1, wherein the trigonal sapphire layer is a (0001) c-planesapphire layer.
 3. The device of claim 2, wherein the (0001) c-planesapphire layer is selected from the group consisting of a bulk singlecrystalline c-plane sapphire wafer, a thin free standing c-planesapphire layer, and a crack-and-bonded c-plane sapphire layer on asubstrate.
 4. The device of claim 2, wherein the hexagonal III-Nitridestructure comprises at least a first p-type layer and at least a firstn-type layer both comprised of AlGaN, InGaN, AlGaInN, AlN, InN or GaN;and the rhombohedral III-V or II-VI structure comprises at least asecond p-type layer and at least a second n-type layer comprised ofAlGaP, InGaP, InAIP, AlGaInP, AlP, InP, GaP, AlGaAs, InGaAs, InAlAs,AlGaInAs, AlAs, InAs, GaAs, AlGaPAs, InGaPAs, InAlPAs, AlGaInPAs, AlPAs,InPAs, or GaPAs.
 5. The device of claim. 4, wherein the hexagonalIII-Nitride structure further comprises at least a first intrinsic layercomprised of AlGaN, InGaN, AlGaInN, AlN, InN, or GaN separating thefirst p-type layer and the first n-type layer; and the rhombohedralIII-V or II-VI structure further comprises at least a second intrinsiclayer comprised of AlGaP, InGaP, InAlP, AlGaInP, AlP, InP, GaP, AlGaAs,InGaAs, InAlAs, AlGaInAs, AlAs, InAs, GaAs, AlGaPAs, InGaPAs, InAlPAs,AlGaInPAs, AlPAs, InPAs, or GaPAs separating the second p-type layer andthe second n-type layer.
 6. The device of claim 5, wherein the firstn-type layer separates the first intrinsic layer and the (0001) c-planesapphire layer; and the second n-type layer separates the secondintrinsic layer and the (0001) c-plane sapphire layer.
 7. The device ofclaim 6, wherein the hexagonal III-Nitride structure further comprises athird intrinsic layer formed on a side of the first p-type layerextending away from the (0001) c-plane sapphire layer and a third n-typelayer formed on a side of the third intrinsic layer extending away fromthe first p-type layer.
 8. The device of claim 7, wherein: the firstintrinsic layer comprises a first intrinsic layer first portion and afirst intrinsic layer second portion; the first p-type layer comprises afirst p-type layer first portion and a first p-type layer secondportion; the first intrinsic layer first portion, the first p-type layerfirst portion, the third intrinsic layer, the third n-type layer, and afirst transparent electrode comprise a first column extending from thefirst n-type layer away from the (0001) c-plane sapphire layer; thefirst intrinsic layer second portion, the first p-type layer secondportion, and a second transparent electrode comprise a second columnextending from the first n-type layer away from the (0001) c-planesapphire layer and separate from the first column; the first transparentelectrode, the third n-type layer, the third intrinsic layer, and thefirst p-type layer first portion comprise a blue LED circuit; the secondtransparent electrode, the first p-type layer second portion, the firstintrinsic layer second portion, and the first n-type layer comprise agreen LED circuit; and the second is-type layer, the second intrinsiclayer, the second p-type layer, and a metal electrode comprise a red LEDcircuit.
 9. The device of claim 5, wherein the first n-type layerseparates the first intrinsic layer and the (0001) c-plane sapphirelayer; and the second p-type layer separates the second intrinsic layerand the (0001) c-plane sapphire layer.
 10. The device of claim 9,wherein the rhombohedral III-V or II-VI structure further comprises athird intrinsic layer formed on a side of the second n-type layerextending away from the (0001) c-plane sapphire layer and a third p-typelayer formed on a side of the third intrinsic layer extending away fromthe second n-type layer.
 11. The device of claim 10, wherein: the thirdp-type layer, the third intrinsic layer, and a first metal electrodecomprise a column extending from the second n-type layer away from the(0001) c-plane sapphire layer; a second metal electrode formed on a sideof the second n-type layer away from the (0001) c-plane sapphire layerand separate from the column; the first metal electrode, the thirdp-type layer, the third intrinsic layer, and the second n-type layercomprise a red LED circuit; the second metal electrode, the secondn-type layer, the second intrinsic layer, and the second p-type layercomprise a green LEE) circuit; and the first n-type layer, the firstintrinsic layer, the first p-type layer, and a transparent electrodecomprise a blue LED circuit.